Obese Kids More Prone to Limb Injuries in Car Crashes

Weaker bones from poor diet, less exercise may be to blame, experts say

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WEDNESDAY, Dec. 10 (HealthDay News) -- During a car crash, American children who are overweight or obese face twice the risk of injury to their arms, legs and feet that normal-weight children do, a new study reveals.

The findings come from a national sample of boys and girls between the ages of 9 and 15.

"Ultimately, motor vehicle crashes are the leading cause of death for all kids in the age range of the study," noted study author Keshia M. Pollack, an assistant professor with the Center for Injury Research and Policy in the department of health policy and management at the Johns Hopkins Bloomberg School of Public Health in Baltimore. "All kids are at equal risk for crashes, regardless of their body size."

"But we showed that once a crash occurs, kids who are obese and overweight are more likely to experience injuries to their extremities," said Pollack, who is also director of the school's Occupational Injury Epidemiology and Prevention Training Program.

The findings are published in the December issue of Injury Prevention.

One in three U.S. children are either overweight or obese, the researchers noted, so the findings could have wide-ranging implications. According to 2006 figures cited by the U.S. Centers for Disease Control and Prevention, more than 12 percent of children between 2 and 5 are obese, a statistic that rises to around 17 percent for those between the ages of 6 and 19.

In the current analysis, the authors crunched numbers gathered by the national Partners for Child Passenger Safety study, conducted between 2000 and 2006. That study focused on more than 3,200 children who had been involved in nearly 2,900 car crashes.

All the children were at least five feet tall and were therefore not using booster seats. All had been in vehicles driven by their parents at the time of the crash. Just over a third of the children were either overweight or obese.

After accounting for potentially mitigating factors -- such as the child's age, sex, and restraint and seating status, as well as the car type, accident type, accident severity, and the driver's age -- the researchers found that there was no significant increase in the overall risk for incurring some kind of moderately severe injury or worse.

However, the risk for incurring a severe injury to the limbs, specifically, was more than two-and-a-half times greater for overweight and obese children versus normal-weight kids.

The connection between excess weight and limb injury risk is the "million dollar question," Pollack said.

"There's not a lot of research that has looked at this, and we were somewhat surprised by the finding," she said. "So now we need to do more biomechanical study to look at the different types of forces in crashes and how they relate to body mass. It could also be that something is going on with physiology in terms of bones and bone strength, and the diminishment of bone strength relative to body weight among obese and overweight kids."

"But clearly, the impact of the association can be dramatic and immediate in terms of car crash injuries," Pollack said, "so we really need to think about this additional consequence of children being overweight and obese."

Lona Sandon is an assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center at Dallas. She believes there are a number of factors related to childhood obesity that might account for the heightened risk.

Sandon noted, for example, that the physical inactivity often associated with being overweight could play a determining role. Inadequate consumption of calcium and/or vitamin D, which are both key to the development of strong bones, is also a hallmark of poor, high-calorie diets, she added.

The study "does underscore that childhood obesity and overweight has large public health implications, and impacts on many health conditions," Sandon said. "And it fits into the overall picture that being overweight entails a risk not just for diabetes and heart disease, but also potentially for bone fractures and other physical injuries that are more immediate."